using System;
using System.IO;
using System.Collections.Generic;
using System.Text;
using System.Net;

namespace eTerm.NetSocket.Net.STUN.Message
{
    /// <summary>
    /// Implements STUN message. Defined in RFC 3489.
    /// </summary>
    public class STUN_Message
    {
        #region enum AttributeType

        /// <summary>
        /// Specifies STUN attribute type.
        /// </summary>
        private enum AttributeType
        {
            MappedAddress    = 0x0001,
            ResponseAddress  = 0x0002,
            ChangeRequest    = 0x0003,
            SourceAddress    = 0x0004,
            ChangedAddress   = 0x0005,
            Username         = 0x0006,
            Password         = 0x0007,
            MessageIntegrity = 0x0008,
            ErrorCode        = 0x0009,
            UnknownAttribute = 0x000A,
            ReflectedFrom    = 0x000B,
            XorMappedAddress = 0x8020,
            XorOnly          = 0x0021,
            ServerName       = 0x8022,
        }

        #endregion

        #region enum IPFamily

        /// <summary>
        /// Specifies IP address family.
        /// </summary>
        private enum IPFamily
        {
            IPv4 = 0x01,
            IPv6 = 0x02,
        }

        #endregion

        private STUN_MessageType     m_Type             = STUN_MessageType.BindingRequest;
        private int                  m_MagicCookie      = 0;
        private byte[]               m_pTransactionID   = null;
        private IPEndPoint           m_pMappedAddress   = null;
        private IPEndPoint           m_pResponseAddress = null;
        private STUN_t_ChangeRequest m_pChangeRequest   = null;
        private IPEndPoint           m_pSourceAddress   = null;
        private IPEndPoint           m_pChangedAddress  = null;
        private string               m_UserName         = null;
        private string               m_Password         = null;
        private STUN_t_ErrorCode     m_pErrorCode       = null;
        private IPEndPoint           m_pReflectedFrom   = null;
        private string               m_ServerName       = null;

        /// <summary>
        /// Default constructor.
        /// </summary>
        public STUN_Message()
        {
            m_pTransactionID = new byte[12];
            new Random().NextBytes(m_pTransactionID);
        }


        #region method Parse

        /// <summary>
        /// Parses STUN message from raw data packet.
        /// </summary>
        /// <param name="data">Raw STUN message.</param>
        /// <exception cref="ArgumentNullException">Is raised when <b>data</b> is null reference.</exception>
        public void Parse(byte[] data)
        {
            if(data == null){
                throw new ArgumentNullException("data");
            }

            /* RFC 5389 6.             
                All STUN messages MUST start with a 20-byte header followed by zero
                or more Attributes.  The STUN header contains a STUN message type,
                magic cookie, transaction ID, and message length.

                 0                   1                   2                   3
                 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
                 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 |0 0|     STUN Message Type     |         Message Length        |
                 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 |                         Magic Cookie                          |
                 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 |                                                               |
                 |                     Transaction ID (96 bits)                  |
                 |                                                               |
                 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              
               The message length is the count, in bytes, of the size of the
               message, not including the 20 byte header.
            */

            if(data.Length < 20){
                throw new ArgumentException("Invalid STUN message value !");
            }

            int offset = 0;

            //--- message header --------------------------------------------------

            // STUN Message Type
            int messageType = (data[offset++] << 8 | data[offset++]);
            if(messageType == (int)STUN_MessageType.BindingErrorResponse){
                m_Type = STUN_MessageType.BindingErrorResponse;
            }
            else if(messageType == (int)STUN_MessageType.BindingRequest){
                m_Type = STUN_MessageType.BindingRequest;
            }
            else if(messageType == (int)STUN_MessageType.BindingResponse){
                m_Type = STUN_MessageType.BindingResponse;
            }
            else if(messageType == (int)STUN_MessageType.SharedSecretErrorResponse){
                m_Type = STUN_MessageType.SharedSecretErrorResponse;
            }
            else if(messageType == (int)STUN_MessageType.SharedSecretRequest){
                m_Type = STUN_MessageType.SharedSecretRequest;
            }
            else if(messageType == (int)STUN_MessageType.SharedSecretResponse){
                m_Type = STUN_MessageType.SharedSecretResponse;
            }
            else{
                throw new ArgumentException("Invalid STUN message type value !");
            }

            // Message Length
            int messageLength = (data[offset++] << 8 | data[offset++]);

            // Magic Cookie
            m_MagicCookie = (data[offset++] << 24 | data[offset++] << 16 | data[offset++] << 8 | data[offset++]);

            // Transaction ID
            m_pTransactionID = new byte[12];
            Array.Copy(data,offset,m_pTransactionID,0,12);
            offset += 12;

            //--- Message attributes ---------------------------------------------
            while((offset - 20) < messageLength){
                ParseAttribute(data,ref offset);
            }
        }

        #endregion

        #region method ToByteData

        /// <summary>
        /// Converts this to raw STUN packet.
        /// </summary>
        /// <returns>Returns raw STUN packet.</returns>
        public byte[] ToByteData()
        {
            /* RFC 5389 6.             
                All STUN messages MUST start with a 20-byte header followed by zero
                or more Attributes.  The STUN header contains a STUN message type,
                magic cookie, transaction ID, and message length.

                 0                   1                   2                   3
                 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
                 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 |0 0|     STUN Message Type     |         Message Length        |
                 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 |                         Magic Cookie                          |
                 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 |                                                               |
                 |                     Transaction ID (96 bits)                  |
                 |                                                               |
                 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              
               The message length is the count, in bytes, of the size of the
               message, not including the 20 byte header.
            */

            // We allocate 512 for header, that should be more than enough.
            byte[] msg = new byte[512];

            int offset = 0;

            //--- message header -------------------------------------

            // STUN Message Type (2 bytes)
            msg[offset++] = (byte)(((int)this.Type >> 8) & 0x3F);
            msg[offset++] = (byte)((int)this.Type & 0xFF);

            // Message Length (2 bytes) will be assigned at last.
            msg[offset++] = 0;
            msg[offset++] = 0;

            // Magic Cookie           
            msg[offset++] = (byte)((this.MagicCookie >> 24) & 0xFF);
            msg[offset++] = (byte)((this.MagicCookie >> 16) & 0xFF);
            msg[offset++] = (byte)((this.MagicCookie >> 8)  & 0xFF);
            msg[offset++] = (byte)((this.MagicCookie >> 0)  & 0xFF);

            // Transaction ID (16 bytes)
            Array.Copy(m_pTransactionID,0,msg,offset,12);
            offset += 12;

            //--- Message attributes ------------------------------------
      
            /* RFC 3489 11.2.
                After the header are 0 or more attributes.  Each attribute is TLV
                encoded, with a 16 bit type, 16 bit length, and variable value:

                0                   1                   2                   3
                0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
               |         Type                  |            Length             |
               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
               |                             Value                             ....
               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            */
            
            if(this.MappedAddress != null){
                StoreEndPoint(AttributeType.MappedAddress,this.MappedAddress,msg,ref offset);
            }
            else if(this.ResponseAddress != null){
                StoreEndPoint(AttributeType.ResponseAddress,this.ResponseAddress,msg,ref offset);
            }
            else if(this.ChangeRequest != null){
                /*
                    The CHANGE-REQUEST attribute is used by the client to request that
                    the server use a different address and/or port when sending the
                    response.  The attribute is 32 bits long, although only two bits (A
                    and B) are used:

                     0                   1                   2                   3
                     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
                    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                    |0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 A B 0|
                    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    The meaning of the flags is:

                    A: This is the "change IP" flag.  If true, it requests the server
                       to send the Binding Response with a different IP address than the
                       one the Binding Request was received on.

                    B: This is the "change port" flag.  If true, it requests the
                       server to send the Binding Response with a different port than the
                       one the Binding Request was received on.
                */
               
                // Attribute header
                msg[offset++] = (int)AttributeType.ChangeRequest >> 8;
                msg[offset++] = (int)AttributeType.ChangeRequest & 0xFF;
                msg[offset++] = 0;
                msg[offset++] = 4;

                msg[offset++] = 0;
                msg[offset++] = 0;
                msg[offset++] = 0;
                msg[offset++] = (byte)(Convert.ToInt32(this.ChangeRequest.ChangeIP) << 2 | Convert.ToInt32(this.ChangeRequest.ChangePort) << 1);               
            }
            else if(this.SourceAddress != null){
                StoreEndPoint(AttributeType.SourceAddress,this.SourceAddress,msg,ref offset);
            }
            else if(this.ChangedAddress != null){
                StoreEndPoint(AttributeType.ChangedAddress,this.ChangedAddress,msg,ref offset);
            }
            else if(this.UserName != null){
                byte[] userBytes = Encoding.ASCII.GetBytes(this.UserName);

                // Attribute header
                msg[offset++] = (int)AttributeType.Username >> 8;
                msg[offset++] = (int)AttributeType.Username & 0xFF;
                msg[offset++] = (byte)(userBytes.Length >> 8);
                msg[offset++] = (byte)(userBytes.Length & 0xFF);

                Array.Copy(userBytes,0,msg,offset,userBytes.Length);
                offset += userBytes.Length;
            }
            else if(this.Password != null){
                byte[] userBytes = Encoding.ASCII.GetBytes(this.UserName);

                // Attribute header
                msg[offset++] = (int)AttributeType.Password >> 8;
                msg[offset++] = (int)AttributeType.Password & 0xFF;
                msg[offset++] = (byte)(userBytes.Length >> 8);
                msg[offset++] = (byte)(userBytes.Length & 0xFF);

                Array.Copy(userBytes,0,msg,offset,userBytes.Length);
                offset += userBytes.Length;
            }
            else if(this.ErrorCode != null){
                /* 3489 11.2.9.
                    0                   1                   2                   3
                    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
                    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                    |                   0                     |Class|     Number    |
                    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                    |      Reason Phrase (variable)                                ..
                    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                */

                byte[] reasonBytes = Encoding.ASCII.GetBytes(this.ErrorCode.ReasonText);

                // Header
                msg[offset++] = 0;
                msg[offset++] = (int)AttributeType.ErrorCode;
                msg[offset++] = 0;
                msg[offset++] = (byte)(4 + reasonBytes.Length);

                // Empty
                msg[offset++] = 0;
                msg[offset++] = 0;
                // Class
                msg[offset++] = (byte)Math.Floor((double)(this.ErrorCode.Code / 100));
                // Number
                msg[offset++] = (byte)(this.ErrorCode.Code & 0xFF);
                // ReasonPhrase
                Array.Copy(reasonBytes,msg,reasonBytes.Length);
                offset += reasonBytes.Length;
            }
            else if(this.ReflectedFrom != null){
                StoreEndPoint(AttributeType.ReflectedFrom,this.ReflectedFrom,msg,ref offset);
            }

            // Update Message Length. NOTE: 20 bytes header not included.
            msg[2] = (byte)((offset - 20) >> 8);
            msg[3] = (byte)((offset - 20) & 0xFF);

            // Make reatval with actual size.
            byte[] retVal = new byte[offset];
            Array.Copy(msg,retVal,retVal.Length);
        
            return retVal;
        }

        #endregion


        #region method ParseAttribute

        /// <summary>
        /// Parses attribute from data.
        /// </summary>
        /// <param name="data">SIP message data.</param>
        /// <param name="offset">Offset in data.</param>
        private void ParseAttribute(byte[] data,ref int offset)
        {
            /* RFC 3489 11.2.
                Each attribute is TLV encoded, with a 16 bit type, 16 bit length, and variable value:

                0                   1                   2                   3
                0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
               |         Type                  |            Length             |
               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
               |                             Value                             ....
               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                            
            */

            // Type
            AttributeType type = (AttributeType)(data[offset++] << 8 | data[offset++]);

            // Length
            int length = (data[offset++] << 8 | data[offset++]);

            // MAPPED-ADDRESS
            if(type == AttributeType.MappedAddress){
                m_pMappedAddress = ParseEndPoint(data,ref offset);
            }
            // RESPONSE-ADDRESS
            else if(type == AttributeType.ResponseAddress){
                m_pResponseAddress = ParseEndPoint(data,ref offset);
            }
            // CHANGE-REQUEST
            else if(type == AttributeType.ChangeRequest){
                /*
                    The CHANGE-REQUEST attribute is used by the client to request that
                    the server use a different address and/or port when sending the
                    response.  The attribute is 32 bits long, although only two bits (A
                    and B) are used:

                     0                   1                   2                   3
                     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
                    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                    |0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 A B 0|
                    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    The meaning of the flags is:

                    A: This is the "change IP" flag.  If true, it requests the server
                       to send the Binding Response with a different IP address than the
                       one the Binding Request was received on.

                    B: This is the "change port" flag.  If true, it requests the
                       server to send the Binding Response with a different port than the
                       one the Binding Request was received on.
                */

                // Skip 3 bytes
                offset += 3;
                                
                m_pChangeRequest = new STUN_t_ChangeRequest((data[offset] & 4) != 0,(data[offset] & 2) != 0);
                offset++;
            }
            // SOURCE-ADDRESS
            else if(type == AttributeType.SourceAddress){
                m_pSourceAddress = ParseEndPoint(data,ref offset);
            }
            // CHANGED-ADDRESS
            else if(type == AttributeType.ChangedAddress){
                m_pChangedAddress = ParseEndPoint(data,ref offset);
            }
            // USERNAME
            else if(type == AttributeType.Username){
                m_UserName = Encoding.Default.GetString(data,offset,length);
                offset += length;
            }
            // PASSWORD
            else if(type == AttributeType.Password){
                m_Password = Encoding.Default.GetString(data,offset,length);
                offset += length;
            }
            // MESSAGE-INTEGRITY
            else if(type == AttributeType.MessageIntegrity){
                offset += length;
            }
            // ERROR-CODE
            else if(type == AttributeType.ErrorCode){
                /* 3489 11.2.9.
                    0                   1                   2                   3
                    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
                    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                    |                   0                     |Class|     Number    |
                    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                    |      Reason Phrase (variable)                                ..
                    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                */

                int errorCode = (data[offset + 2] & 0x7) * 100 + (data[offset + 3] & 0xFF);

                m_pErrorCode = new STUN_t_ErrorCode(errorCode,Encoding.Default.GetString(data,offset + 4,length - 4));
                offset += length;
            }
            // UNKNOWN-ATTRIBUTES
            else if(type == AttributeType.UnknownAttribute){
                offset += length;
            }
            // REFLECTED-FROM
            else if(type == AttributeType.ReflectedFrom){
                m_pReflectedFrom = ParseEndPoint(data,ref offset);
            }
            // XorMappedAddress
            // XorOnly
            // ServerName
            else if(type == AttributeType.ServerName){
                m_ServerName = Encoding.Default.GetString(data,offset,length);
                offset += length;
            }
            // Unknown
            else{
                offset += length;
            }
        }

        #endregion

        #region method ParseEndPoint

        /// <summary>
        /// Pasrses IP endpoint attribute.
        /// </summary>
        /// <param name="data">STUN message data.</param>
        /// <param name="offset">Offset in data.</param>
        /// <returns>Returns parsed IP end point.</returns>
        private IPEndPoint ParseEndPoint(byte[] data,ref int offset)
        {
            /*
                It consists of an eight bit address family, and a sixteen bit
                port, followed by a fixed length value representing the IP address.

                0                   1                   2                   3
                0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
                +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                |x x x x x x x x|    Family     |           Port                |
                +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                |                             Address                           |
                +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            */

            // Skip family
            offset++;
            offset++;
            
            // Port
            int port = (data[offset++] << 8 | data[offset++]);

            // Address
            byte[] ip = new byte[4];
            ip[0] = data[offset++];
            ip[1] = data[offset++];
            ip[2] = data[offset++];
            ip[3] = data[offset++];
            
            return new IPEndPoint(new IPAddress(ip),port);
        }

        #endregion

        #region method StoreEndPoint

        /// <summary>
        /// Stores ip end point attribute to buffer.
        /// </summary>
        /// <param name="type">Attribute type.</param>
        /// <param name="endPoint">IP end point.</param>
        /// <param name="message">Buffer where to store.</param>
        /// <param name="offset">Offset in buffer.</param>
        private void StoreEndPoint(AttributeType type,IPEndPoint endPoint,byte[] message,ref int offset)
        {
            /*
                It consists of an eight bit address family, and a sixteen bit
                port, followed by a fixed length value representing the IP address.

                0                   1                   2                   3
                0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
                +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                |x x x x x x x x|    Family     |           Port                |
                +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                |                             Address                           |
                +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+             
            */

            // Header
            message[offset++] = (byte)((int)type >> 8);
            message[offset++] = (byte)((int)type & 0xFF); 
            message[offset++] = 0;
            message[offset++] = 8;
                   
            // Unused
            message[offset++] = 0;
            // Family
            message[offset++] = (byte)IPFamily.IPv4;
            // Port
            message[offset++] = (byte)(endPoint.Port >> 8);
            message[offset++] = (byte)(endPoint.Port & 0xFF);
            // Address
            byte[] ipBytes = endPoint.Address.GetAddressBytes();
            message[offset++] = ipBytes[0];
            message[offset++] = ipBytes[1];
            message[offset++] = ipBytes[2];
            message[offset++] = ipBytes[3];
        }

        #endregion


        #region Properties Implementation

        /// <summary>
        /// Gets STUN message type.
        /// </summary>
        public STUN_MessageType Type
        {
            get{ return m_Type; }

            set{ m_Type = value; }
        }

        /// <summary>
        /// Gets magic cookie value. This is always 0x2112A442.
        /// </summary>
        public int MagicCookie
        {
            get{ return m_MagicCookie; }
        }

        /// <summary>
        /// Gets transaction ID.
        /// </summary>
        public byte[] TransactionID
        {
            get{ return m_pTransactionID; }
        }

        /// <summary>
        /// Gets or sets IP end point what was actually connected to STUN server. Returns null if not specified.
        /// </summary>
        public IPEndPoint MappedAddress
        {
            get{ return m_pMappedAddress; }

            set{ m_pMappedAddress = value; }
        }

        /// <summary>
        /// Gets or sets IP end point where to STUN client likes to receive response.
        /// Value null means not specified.
        /// </summary>
        public IPEndPoint ResponseAddress
        {
            get{ return m_pResponseAddress; }

            set{ m_pResponseAddress = value; }
        }

        /// <summary>
        /// Gets or sets how and where STUN server must send response back to STUN client.
        /// Value null means not specified.
        /// </summary>
        public STUN_t_ChangeRequest ChangeRequest
        {
            get{ return m_pChangeRequest; }

            set{ m_pChangeRequest = value; }
        }

        /// <summary>
        /// Gets or sets STUN server IP end point what sent response to STUN client. Value null
        /// means not specified.
        /// </summary>
        public IPEndPoint SourceAddress
        {
            get{ return m_pSourceAddress; }

            set{ m_pSourceAddress = value; }
        }

        /// <summary>
        /// Gets or sets IP end point where STUN server will send response back to STUN client 
        /// if the "change IP" and "change port" flags had been set in the ChangeRequest.
        /// </summary>
        public IPEndPoint ChangedAddress
        {
            get{ return m_pChangedAddress; }

            set{ m_pChangedAddress = value; }
        }
        
        /// <summary>
        /// Gets or sets user name. Value null means not specified.
        /// </summary>          
        public string UserName
        {
            get{ return m_UserName; }

            set{ m_UserName = value; }
        }

        /// <summary>
        /// Gets or sets password. Value null means not specified.
        /// </summary>
        public string Password
        {
            get{ return m_Password; }

            set{ m_Password = value; }
        }

        //public MessageIntegrity

        /// <summary>
        /// Gets or sets error info. Returns null if not specified.
        /// </summary>
        public STUN_t_ErrorCode ErrorCode
        {
            get{ return m_pErrorCode; }

            set{ m_pErrorCode = value; }
        }


        /// <summary>
        /// Gets or sets IP endpoint from which IP end point STUN server got STUN client request.
        /// Value null means not specified.
        /// </summary>
        public IPEndPoint ReflectedFrom
        {
            get{ return m_pReflectedFrom; }

            set{ m_pReflectedFrom = value; }
        }

        /// <summary>
        /// Gets or sets server name.
        /// </summary>
        public string ServerName
        {
            get{ return m_ServerName; }

            set{ m_ServerName = value; }
        }

        #endregion

    }
}
